1. Field of the Invention
The present invention relates to a recording apparatus for use with an optical disc or the like, a recording method thereof, and a disc-shaped recording medium.
2. Description of the Related Art
Disc-shaped record mediums (for example, DVDs) can be categorized as rewritable mediums (DVD+RW) and read-only mediums (DVD-ROM) depending on their characteristics. Since their physical formats are similar, it is preferable to allow a DVD-ROM drive to reproduce data from a DVD+RW disc. There are differences between the DVD+RW drive and the DVD-ROM drive in a spindle servo signal and a method for obtaining a position signal (address) of a medium. The DVD+RW disc has a wobbling groove. The DVD+RW drive obtains a position signal from a reproduced signal of the wobbling groove. In contrast, the DVD-ROM disc does not have such a wobbling groove. The DVD-ROM drive obtains a position signal from a frame synchronous signal and an address signal reproduced from the DVD-ROM disc.
To allow the DVD-ROM drive to reproduce data from the DVD-RW disc, a frame synchronous signal and a position signal are placed in data of the DVD+RW disc. However, since the DVD+RW disc has a non-recorded portion before or after recorded data, it is difficult for the DVD-ROM drive to reproduce data from the DVD+RW disc. In reality, since the DVD-ROM drive cannot reproduce the frame synchronous signal from the DVD+RW disc, the DVD-ROM cannot stably operate the spindle servo and perform the seek operation for reading a desired sector from the DVD+RW disc.
The seek operation is performed in a combination of a coarse seek operation and a fine seek operation. In the coarse servo operation, many tracks are jumped at a time. On the other hand, in the fine servo operation, a desired sector is acquired in the vicinity of a target position. Due to the eccentricity of the disc, when the seek operation is performed in the fine servo operation, a deviation of several ten tracks to several hundred tracks normally takes place. If the jumped position is a non-recorded area, the target track cannot be acquired. Thus, when the seek operation is performed, data containing a frame synchronous signal and a position signal should have been recorded in the vicinity of the target sector.
Thus, to allow the DVD-ROM drive to reproduce data from the DVD+RW disc, dummy data should have been recorded before or after recorded data on the DVD+RW. To do that, a process referred to as a finalizing process is performed. The finalizing process can be performed in the following two methods.
As the first method, a file system is analyzed. Generally, a file system has a space bit map for allocating a user area. A UDF system that is often used for DVD discs has a space bit map and information that represents whether or not each entry of each file has been recorded. Thus, when the file system is analyzed, a position of user data (namely, a position to which dummy data should be written) can be obtained. This method is performed by an application program of a host computer.
As the second method, a blank area is detected. In this method, all blocks of the DVD+RW disc are read. When a block can be read, it is treated as a recorded block. On the other hand, when a block cannot be read, the hardware of the drive determines whether an RF signal is absent (namely, data has been recorded) or data that has been recorded cannot be reproduced. When the RF signal cannot be obtained, since data has not been recorded, dummy data is recorded. Even if the RF signal is obtained, when data cannot be read, the drive determines whether the relevant block is unchanged or dummy data is overwritten depending on the amount of an ECC error or the like.
The first method (for analyzing a file system for use) can be effectively performed as long as the number of directories/files is small. However, when the number of directories/files is as large as several thousands, it takes a long time to perform the process. Thus, this method is not effective. In the file system other than the UDF system, this method cannot be used because available information is limited to allocation information. In other words, depending on a file system for use, the feasibility of this method is restricted. On the other hand, the second method (for detecting a blank area) can be used regardless of a file system for use. However, since all blocks of the disc should be read, it takes a long time to perform the process.
Other than the above-described two methods, when a disc is formed, a certificating process may be required. In the certificating process, a certification pattern is recorded on the entire disc. By reproducing the data, it is determined whether or not there is a defect on the disc. Thus, when the certification pattern is recorded on the entire surface, since non-recorded areas are absent, the finalizing process is not required. However, since the storage capacity of the DVD+RW disc is large, it takes around one hour to perform the certificating process. Thus, since this method is not effective, it is improper to require the user to perform the certificating process.